The objective of the proposed work is to identify and synthesize non-K-region dihydrodiols and their related diol-epoxides that are derived from polycyclic aromatic hydrocarbons and that may be involved in reactions with cellular nucleic acids. The investigations will be concerned with a number of hydrocarbons other than benzo(a)pyrene that have not yet been examined in detail and will include benz(a)anthracene, 7-methylbenz(a)anthracene, 7,12-dimethylbenz(a)anthracene, 3-methylcholanthrene and dibenz(a,h)anthracene. The formation of dihydrodiols and diol-epoxides from the hydrocarbons in model metabolizing systems such as rat-liver microsomal systems and also in target tissues such as mouse skin will be investigated. The metabolites will be identified by comparison of their spectral properties and their properties on high pressure liquid chromatograms with the properties of the authentic compounds. The long term aim of the work is to understand the way in which the modification of nucleic acids by polycyclic hydrocarbon metabolites causes biological effects such as mutagenesis and carcinogenesis.